Is it possible to add GDC compiler?

[Behkar]

Given that the new front end is GDC with D, I compiled it with GDC, the result was:

○ → dub --compiler=gdc

gdc: error: unrecognized command-line option ‘-run’
Command failed with exit code 1: gdc -run scripts/generate_version.d‍‍‍```

[s-ludwig]

This is actually an error in deimos-openssl, which needs to be specialized for GDC by separating the operation into build and run.

To work around this error, it should be possible to use one of "openssl-1.1", "openssl-static" or "notls" as the build configuration of vibe-d:tls (i.e. by adding dependency "vibe-d:tls" version="*"; subConfiguration "vibe-d:tls" "notls" or similar).

I'm not sure whether anything else currently fails with GDC, but we should definitely add it back to the CI if possible.